Liquid crystal display device

ABSTRACT

A liquid crystal display device for eliminating a vertical dimming phenomenon to improve a picture quality of a liquid crystal display panel is disclosed. In the device, first and second data lines are supplied with data. A first pixel electrode is spaced at a desired distance from the first data line. A second pixel electrode is spaced, by a distance different from said distance between the first data line and the first pixel electrode, from the second data line.

This is a Divisional Application of U.S. patent application Ser. No.10/811,141, filed on Mar. 29, 2004 now U.S. Pat. No. 7,511,791; whichclaims priority of Korean Patent Application No. P2003-19532, filed onMar. 28, 2003, all of which are incorporated herein by reference intheir entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a liquid crystal display, and moreparticularly to a liquid crystal display that is adapted to eliminate avertical dimming phenomenon to improve a picture quality of a liquidcrystal display panel.

2. Description of the Related Art

Generally, a liquid crystal display (LCD) controls the lighttransmittance of a liquid crystal using an electric field to therebydisplay a picture. To achieve this, the LCD includes a liquid crystaldisplay panel having liquid crystal cells arranged in a matrix, and adriving circuit for driving the liquid crystal display panel. In theliquid crystal display panel, gate lines and data lines cross each otherand liquid crystal cells are provided at areas defined by such crossingsof the gate lines with the data lines. The liquid crystal display panelis provided with transparent pixel electrodes and a common electrode forapplying an electric field to the liquid crystal cells. Each pixelelectrode is connected, via source and drain terminals of a thin filmtransistor (TFT) as a switching device, to any one of the data lines.The gate terminal of the TFT is connected to any one of the gate lines.Accordingly, the LCD controls the light transmittance by an electricfield applied between the pixel electrode and the common electrode inresponse to a data voltage signal supplied for each liquid crystal cell,to display a picture.

Such an LCD uses inversion driving schemes, such as a frame inversionsystem, a line (or column) inversion system and a dot inversion system,in order to drive the liquid crystal cells in the liquid crystal displaypanel. The frame inversion system inverts the polarities of data signalsapplied to the liquid crystal cells in the liquid crystal display panelwhenever a frame is changed. The line inversion system inverts thepolarities of data signals applied to the liquid crystal cells inaccordance with the lines (or columns) on the liquid crystal displaypanel. The dot inversion system allows data signals having polaritiescontrary to that of the data signals applied to the liquid crystal cellsadjacent to each other in the vertical and horizontal directions to beapplied to the liquid crystal cells in the liquid crystal display panel,and allows the polarities of data signals applied to all the liquidcrystal cells in the liquid crystal display panel to be inverted everyframe. The dot inversion system of such inversion driving schemesprovides a picture having a better picture quality than that of theframe and line inversion systems.

Typically, such an LCD is driven with a frame frequency of 60 Hz.However, a system requiring low power consumption such as a notebookpersonal computer requires lowering the frame frequency from 50 to 30Hz. Since the dot inversion system capable of providing an excellentpicture quality described with reference to the above-mentionedinversion systems also generates a flicker as the frame frequencydecreases a liquid crystal display panel driving method having ahorizontal 2-dot inversion system as shown in FIG. 1A and FIG. 1B.

Referring to FIG. 1A and FIG. 1B, there are shown data polarity patternsapplied to the liquid crystal cells in the liquid crystal display panelby the liquid crystal display panel driving method employing thehorizontal 2-dot inversion system, which are divided into odd frames andeven frames, respectively. With respect to the odd frames shown in FIG.1A and the even frames shown in FIG. 1B, the data polarity pattern inthe horizontal 2-dot inversion driving system is changed for each twoliquid crystal cells, that is, for each two dots in the horizontaldirection while being changed for each one dot in the verticaldirection.

If such a horizontal 2-dot inversion system is used, then a phenomenonthat DC voltage concentrates on the data line from almost a majority ofthe screen is eliminated because an identical period between colors ofred (R), green (G) and blue (B) pixels and data polarity patternsbecomes 12 dots in the horizontal direction, thereby reducing a flicker.However, a use of the horizontal 2-dot inversion system causes abrightness difference between odd-numbered lines and even-numbered linesof the data lines from the gray field, thereby generating a verticaldimming phenomenon.

The above-mentioned vertical dim caused by the horizontal 2-dotinversion driving is generated by a parasitic capacitance between thedata line and the pixel electrode. This will be described in detail inconjunction with FIG. 2 below.

Referring to FIG. 2 and FIG. 3, a liquid crystal cell of theconventional LCD includes thin film transistors TFT provided atcrossings between data lines DL and gate lines GL, and pixel electrodesPE connected to common electrodes Vcom and the thin film transistors TFTopposed to each other with having a liquid crystal therebetween.

The thin film transistor TFT has a gate electrode connected to the gateline GL, a source electrode connected to the data line DL and a drainelectrode connected to the pixel electrode PE. The thin film transistorTFT is turned on when a scanning signal, that is, a gate high voltageVgh from the gate line GL, is applied, to thereby supply the liquidcrystal cell with a pixel signal from the data line DL. Further, thethin film transistor TFT is turned off when a gate low voltage Vgl fromthe gate line GL is applied, to thereby maintain a pixel signal chargedin the liquid crystal cell.

The liquid crystal cell further includes a storage capacitor Cst inorder to maintain the charged pixel electrode PE until the next pixelsignal is charged. This storage capacitor Cst is provided between thepixel electrode PE and the pre-stage gate line GLn−1. Such a liquidcrystal cell varies an alignment state of a liquid crystal cell inresponse to a pixel signal charged via the thin film transistor TFT forthe purpose of controlling a light transmittance, thereby implementing agray level.

As shown in FIG. 3, the liquid crystal cell can be equivalentlyexpressed as a liquid crystal capacitor Clc, which generates a parasiticcapacitance because it is adjacent to the data line DL and the pixelelectrode PE. In this case, the parasitic capacitance includes a firstparasitic capacitance Cdp between the left data line DLm−1 and the pixelelectrode PE, and a second parasitic capacitance Cpd between the pixelelectrode PE and the left data line DLm. Each of the first and secondparasitic capacitance Cdp and Cpd causes a voltage variation in the dataline and a capacitance coupling after a pixel signal is charged in theliquid crystal cell, thereby varying a voltage of the liquid crystalcell.

In other words, if the liquid crystal cell is driven by the horizontal2-dot inversion system, then two pixels having the same data polaritypattern of the data signal differ by an average variation value ΔVp−dpof a pixel voltage A caused by a capacitance coupling of the firstparasitic capacitance Cdp from an average variation value ΔVp−pd of apixel voltage B caused by a capacitance coupling of the second parasiticcapacitance Cpd, as shown in FIG. 4, with respect to a left pixel 10 anda light pixel 20.

In this case, an average variation value ΔVp−dp of a pixel voltage Acaused by a capacitance coupling of the first parasitic capacitance Cdpor an average variation value ΔVp−pd of a pixel voltage B caused by acapacitance coupling of the second parasitic capacitance Cpd can beexpressed by the following equation:ΔVp(Cdp or Cpd)={Cdp×ΔV(DL _(m)−1)+Cpd×ΔV(DL _(m))}÷^(C)total  (1)

wherein ^(C)total represents total capacitance of the pixel electrodePE.

Accordingly, at the right pixel 20, the values are cancelled withrespect to each other like the dot inversion driving system. On theother hand, at the left pixel 10, an average variation value ΔVp−dp of apixel voltage A caused by a capacitance coupling of the first parasiticcapacitance Cdp is added to an average variation value ΔVp−pd of a pixelvoltage B caused by a capacitance coupling of the second parasiticcapacitance Cpd at the left pixel 10 without being cancelled. Thus,average variation values of the pixel voltages caused by the capacitancecouplings at the left pixel 10 and at the light pixel 20 becomedifferent from each other.

Consequently, when the first parasitic capacitance Cdp is equal to thesecond parasitic capacitance Cpd, an effective value of the pixelvoltage at the left pixel 10 becomes two times of ΔVp−dp in comparisonwith that at the light pixel 20. In this case, an effective valuevariation in the pixel voltage increases when the pixel voltage has apositive level, whereas an effective value variation in the pixelvoltage decreases when the pixel voltage has a negative level.Accordingly, there occurs a phenomenon that the right pixel 20 becomesbrighter than the left pixel 10 as shown in FIG. 5. As a result, the LCDemploying the horizontal 2-dot inversion driving system generates avertical dim (or vertical line) from the liquid crystal display panel.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a liquid crystaldisplay device that substantially obviates one or more of the problemsdue to limitations and disadvantages of the related art.

It is an advantage of the present invention to provide a liquid crystaldisplay that is adaptive for eliminating a vertical dim phenomenon toimprove a picture quality of a liquid crystal display panel.

In order to achieve these and other advantages of the invention, aliquid crystal display device according to an embodiment of the presentinvention includes first and second data lines supplied with data; afirst pixel electrode spaced at a desired distance from the first dataline; and a second pixel electrode spaced, by a distance different fromsaid distance between the first data line and the first pixel electrode,from the second data line.

In the liquid crystal display device, the second pixel electrode has alarger dimension that the first pixel electrode.

The first and second pixel electrodes are supplied with data having thesame polarity.

Said data have data polarity patterns inverted for each two pixelelectrodes in the horizontal direction while having data polaritypatterns inverted for each one pixel electrode in the verticaldirection.

Herein, a parasitic capacitance between the second pixel electrode andthe second data line has at least three times larger value than aparasitic capacitance between the first pixel electrode and the firstdata line.

A liquid crystal display device according to another embodiment of thepresent invention includes a first data line supplied with data; and asecond data line supplied with said data and having a different widthfrom the first data line.

The liquid crystal display device further includes a first pixelelectrode spaced at a desired distance from the first data line; and asecond pixel electrode spaced at a desired distance from the second dataline.

In the liquid crystal display device, the first pixel electrode has thesame dimension as the second pixel electrode.

The first and second pixel electrodes are supplied with data having thesame polarity.

Said data have data polarity patterns inverted for each two pixelelectrodes in the horizontal direction while having data polaritypatterns inverted for each one pixel electrode in the verticaldirection.

Herein, a parasitic capacitance between the second pixel electrode andthe second data line has at least three times larger value than aparasitic capacitance between the first pixel electrode and the firstdata line.

A liquid crystal display device according to still another embodiment ofthe present invention includes a first data line supplied with data; asecond data line supplied with said data and being in parallel to thefirst data line; and a protrusion electrode protruded from the seconddata line.

The liquid crystal display device further includes a first pixelelectrode spaced at a desired distance from the first data line; and asecond pixel electrode spaced at a desired distance from the second dataline and overlapped with the protrusion electrode at a portion thereof.

In the liquid crystal display device, the first pixel electrode has thesame dimension as the second pixel electrode.

The first and second pixel electrodes are supplied with data having thesame polarity.

Said data have data polarity patterns inverted for each two pixelelectrodes in the horizontal direction while having data polaritypatterns inverted for each one pixel electrode in the verticaldirection.

Herein, a parasitic capacitance between the second pixel electrode andthe second data line and a parasitic capacitance between the protrusionelectrode and the second pixel electrode have at least three timeslarger value than a parasitic capacitance between the first pixelelectrode and the first data line.

A liquid crystal display device according to still another embodiment ofthe present invention includes first and second data lines supplied withdata; a first pixel electrode spaced at a desired distance from thefirst data line; a second pixel electrode spaced at a desired distancefrom the second data line; and a protrusion electrode protruded from thesecond pixel electrode into the second data line and overlapped at aportion thereof.

In the liquid crystal display device, the first pixel electrode has thesame dimension as the second pixel electrode.

The first and second pixel electrodes are supplied with data having thesame polarity.

Said data have data polarity patterns inverted for each two pixelelectrodes in the horizontal direction while having data polaritypatterns inverted for each one pixel electrode in the verticaldirection.

Herein, a parasitic capacitance between the second pixel electrode andthe second data line and a parasitic capacitance between the protrusionelectrode and the second pixel electrode have at least three timeslarger value than a parasitic capacitance between the first pixelelectrode and the first data line.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1A and FIG. 1B depict data polarity patterns in a horizontal 2-dotinversion system applied to a related art liquid crystal display panel;

FIG. 2 is a schematic view illustrating a liquid crystal cellconfiguration of a related art liquid crystal display device;

FIG. 3 is an equivalent circuit diagram of the liquid crystal cellillustrated in FIG. 2;

FIG. 4 is a waveform diagram representing a variation in a pixel voltagecaused by a parasitic capacitance of the liquid crystal cell shown inFIG. 3;

FIG. 5 depicts a vertical dim phenomenon displayed on the liquid crystaldisplay panel by a capacitance coupling effect caused by the data lineand the parasitic capacitance shown in FIG. 3;

FIG. 6 is a schematic diagram illustrated a liquid crystal cellconfiguration having an asymmetrical pixel electrode in a liquid crystaldisplay device according to a first embodiment of the present invention;

FIG. 7 is an equivalent circuit diagram of the liquid crystal cellillustrated in FIG. 6;

FIG. 8 is a schematic diagram illustrating a liquid crystal cellconfiguration of a liquid crystal display device according to a secondembodiment of the present invention;

FIG. 9 is a schematic diagram illustrating a liquid crystal cellconfiguration of a liquid crystal display device according to a thirdembodiment of the present invention; and

FIG. 10 is a schematic diagram illustrating a liquid crystal cellconfiguration of a liquid crystal display device according to a fourthembodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT

Reference will now be made in detail to an embodiment of the presentinvention, example of which is illustrated in the accompanying drawings.

Referring to FIG. 6 and FIG. 7, a liquid crystal cell of a liquidcrystal display (LCD) according to a first embodiment of the presentinvention includes thin film transistors TFT provided at crossingsbetween data lines DL and gate lines GL, and transparent pixelelectrodes PE provided between adjacent data lines DL in such a mannerto have a different distance from the data lines DL. The liquid crystalcell further includes a storage capacitor Cst in order to make a stablemaintenance of the charged pixel electrode PE until the next pixelsignal is charged.

The thin film transistor TFT has a gate electrode connected to the gateline GL, a source electrode connected to the data line DL and a drainelectrode connected to the pixel electrode PE. The thin film transistorTFT is turned on when a scanning signal, that is, a gate high voltageVgh from the gate line GL is applied, to thereby supply the liquidcrystal cell with a pixel signal from the data line DL. Further, thethin film transistor TFT is turned off when a gate low voltage Vgl fromthe gate line GL is applied, to thereby maintain a pixel signal chargedin the liquid crystal cell.

The pixel electrode PE is connected to a common electrode Vcom and thethin film transistor TFT that are opposed to each other with having aliquid crystal therebetween. Such a pixel electrode PE is comprised of afirst pixel electrode PE1 spaced at a desired distance from the (m−1)thdata line DLm−1, and a second pixel electrode PE2 spaced, by a distancedifferent from the distance between the (m−1)th data line DLm−1 and thefirst pixel electrode PE1, from the mth data line DLm.

The first and second pixel electrodes PE1 and PE2 have a different size(or area) from each other. Herein, the second pixel electrode PE2 has alarger area than the first pixel electrode PE1.

The first pixel electrode PE1 is provided between the (m−1)th data lineDLm−1 and the mth data line DLm such that a distance between one sidethereof and the (m−1)th data line DLm−1 is equal to a distance betweenother opposite side thereof and the mth data line DLm. In this case, aparasitic capacitance is generated between the data line DL and thepixel electrode PE because they are structurally adjacent to each other.Such a parasitic capacitance causes a voltage variation in the data lineand a capacitance coupling after a pixel signal was charged in theliquid crystal cell, thereby varying a pixel voltage of the liquidcrystal cell. The parasitic capacitance is divided into a firstparasitic capacitance Cdp1 generated between the (m−1)th data line andthe first pixel electrode PE1 and a second parasitic capacitance Cpd1generated between the first pixel electrode PE1 and the mth data lineDLm.

The second pixel electrode PE2 is provided between the mth data line DLmand the (m+1)th data line DLm+1 such that a distance between one sidethereof and the mth data line DLm is equal to a distance between otheropposite side thereof and the (m+1)th data line DLm+1. In other words,one side of the second pixel electrode PE2 adjacent to the mth data lineDLm is further extended into the mth data line DLm. In this case, athird parasitic capacitance Cdp2 is generated between the mth data lineDLm and the second pixel electrode PE2 while a fourth parasiticcapacitance Cpd2 is generated between the second pixel electrode PE2 andthe (m+1)th data line DLm+1. Thus, the third parasitic capacitance Cdp2is at least three times larger than the first parasitic capacitance Cdp1of the first pixel electrode PE1. In other words, a distance W2 betweenone side of the second pixel electrode PE2 and the mth data line DLmbecomes narrower than a width W1 between one side of the first pixelelectrode PE1 and the (m−1)th data line DLm−1. Thus, the third parasiticcapacitance Cdp2 is at least three times larger than the first parasiticcapacitance Cdp1. On the other hand, the fourth parasitic capacitanceCpd2 has the same value as the first parasitic capacitance Cdp1.

The liquid crystal cell provided with the first and second pixelelectrodes PE1 and PE2 is supplied with a data polarity pattern in thehorizontal 2-dot inversion driving system that is changed every twoliquid crystal cells, i.e., for each two dots in the horizontaldirection while being changed for each one dot in the verticaldirection. Accordingly, the first pixel electrode PE1 and the secondpixel electrode PE2 are supplied with the same data polarity pattern.

As described above, when the liquid crystal cell is driven by thehorizontal 2-dot inversion system, the LCD according to the firstembodiment of the present invention allows the third parasiticcapacitance Cdp2 at a right pixel 120, of two pixels having the samedata polarity pattern, to be three times greater than the firstparasitic capacitance Cdp1. Accordingly, at a left pixel 110, an effectcaused by a capacitance coupling of the first parasitic capacitance Cdp1is added to an effect caused by a capacitance coupling of the secondparasitic capacitance Cpd1. On the other hand, at the right pixel 120,an effect caused by a capacitance coupling of the fourth parasiticcapacitance Cpd2 is subtracted from an effect caused by a capacitancecoupling of the third parasitic capacitance Cdp2, but an effect causedby the same capacitance coupling as the left pixel 110 only is leftbecause an effect caused by a capacitance coupling of the thirdparasitic capacitance Cdp2 is relatively large. Thus, a deviation in thepixel voltage of the left pixel 110 and the right pixel 120 in the datapolarity pattern is cancelled. Accordingly, the LCD according to theembodiment of the present invention does not generate a vertical dimmingphenomenon caused by the parasitic capacitance between the data line andthe pixel electrode in the related art.

Referring to FIG. 8, a liquid crystal cell of a liquid crystal display(LCD) according to a second embodiment of the present invention includesthin film transistors TFT provided at crossings between data lines DLand gate lines GL having a different widths, and pixel electrodes PEconnected to the thin film transistor TFT. The liquid crystal cellfurther includes a storage capacitor Cst in order to maintain thecharged pixel electrode PE until the next pixel signal is charged.

The thin film transistor TFT has a gate electrode connected to the gateline GL, a source electrode connected to the data line DL and a drainelectrode connected to the pixel electrode PE. The thin film transistorTFT is turned on when a scanning signal, that is, a gate high voltageVgh from the gate line GL is applied, to thereby supply the liquidcrystal cell with a pixel signal from the data line DL. Further, thethin film transistor TFT is turned off when a gate low voltage Vgl fromthe gate line GL is applied, to thereby maintain a pixel signal chargein the liquid crystal cell.

The data lines DL includes a first data line DLm−1 having a first widthW1, and a second data line DLm having a second width W2 larger than thefirst width W1 and provided in parallel to the first data line DLm−1.The first and second data lines DLm−1 and DLm are repeatedly provided tohave the same distance.

The pixel electrode PE is provided between the data lines DL andconnected to the thin film transistor TFT.

At a left pixel 110 provided at the left side around the second dataline DLm in the liquid crystal cell, a first parasitic capacitance Cdp1is generated between the first data line DLm−1 and the pixel electrodePE while a second parasitic capacitance Cpd1 is generated between thepixel electrode PE and the second data line DLm. On the other hand, at aright pixel 120 provided at the right side of the second data line DLmin the liquid crystal cell, a third parasitic capacitance Cdp2 isgenerated between the second data line DLm and the pixel electrode PEwhile a fourth parasitic capacitance Cpd2 is generated between the pixelelectrode PE and the first data line DLm+1.

Thus, the third parasitic capacitance Cdp2 of the right pixel 120 is atleast three times greater than the first parasitic capacitance Cdp1 ofthe left pixel 110. To this end, a width W2 of the second data line DLmis set to be larger than a width W1 of the first data line DLm−1 withina width range of a black matrix (not shown). Thus, the third parasiticcapacitance Cdp2 is at least three times greater than the firstparasitic capacitance Cdp1 because a distance between the second dataline DLm and the pixel electrode PE is shorter than a distance betweenthe first data line DLm−1 and the pixel electrode PE.

As described above, when the liquid crystal cell is driven by thehorizontal 2-dot inversion system, the LCD according to the secondembodiment of the present invention allows the third parasiticcapacitance Cdp2 at a right pixel 120 of two pixels having the same datapolarity pattern to be three times greater than the first parasiticcapacitance Cdp1. Accordingly, at a left pixel 110, an effect caused bya capacitance coupling of the first parasitic capacitance Cdp1 is addedto an effect caused by a capacitance coupling of the second parasiticcapacitance Cpd1. On the other hand, at the right pixel 120, an effectcaused by a capacitance coupling of the fourth parasitic capacitanceCpd2 is subtracted from an effect caused by a capacitance coupling ofthe third parasitic capacitance Cdp2, but an effect caused by the samecapacitance coupling as the left pixel 110 only is left because aneffect caused by a capacitance coupling of the third parasiticcapacitance Cdp2 is relatively large. Thus, a deviation in the pixelvoltage of the left pixel 110 and the right pixel 120 in the datapolarity pattern is cancelled. Accordingly, the LCD according to theembodiment of the present invention does not generate a vertical dimmingphenomenon caused by the parasitic capacitance between the data line andthe pixel electrode in the related art.

Referring to FIG. 9, a liquid crystal cell of a liquid crystal display(LCD) according to a third embodiment of the present invention includesthin film transistors TFT provided at crossings of data lines DL andgate lines GL having a different width from each other, and pixelelectrodes PE connected to the thin film transistor TFT. The liquidcrystal cell further includes a storage capacitor Cst in order to make astable maintenance of the charged pixel electrode PE until the nextpixel signal is charged.

The thin film transistor TFT has a gate electrode connected to the gateline GL, a source electrode connected to the data line DL and a drainelectrode connected to the pixel electrode PE. The thin film transistorTFT is turned on when a scanning signal, that is, a gate high voltageVgh from the gate line GL is applied, to thereby supply the liquidcrystal cell with a pixel signal from the data line DL. Further, thethin film transistor TFT is turned off when a gate low voltage Vgl fromthe gate line GL is applied, to thereby maintain a pixel signal chargedin the liquid crystal cell.

The data lines DL include a first data line DLm−1, and a second dataline DLm provided substantially in parallel to the first data line DLm−1and having a protrusion electrode 200 extending from the pixel electrodePE at one side thereof and overlapping with the pixel electrode PE at aportion thereof. The first and second data lines DLm−1 and DLm arerepeatedly provided to have the same distance.

The pixel electrode PE is provided between the data lines DL andconnected to the thin film transistor TFT.

At a left pixel 110 provided at the left side around the second dataline DLm in the liquid crystal cell, a first parasitic capacitance Cdp1is generated between the first data line DLm−1 and the pixel electrodePE while a second parasitic capacitance Cpd1 is generated between thepixel electrode PE and the second data line DLm. At a right pixel 120provided at the right side around the second data line DLm in the liquidcrystal cell, a third parasitic capacitance Cdp2 is generated betweenthe second data line DLm and the pixel electrode PE while a fourthparasitic capacitance Cpd2 is generated between the pixel electrode PEand the first data line DLm+1. Further, at the right pixel 120, thepixel electrode PE overlaps with the protrusion electrode 200 of thesecond data line DLm to thereby generate an additional capacitance 202.

Thus, the third parasitic capacitance Cdp2 and the additionalcapacitance 202 generated between the second data line DLm and the pixelelectrode PE at the right pixel 120 is at least three times greater thanthe first parasitic capacitance Cdp1. To this end, the protrusionelectrode 200 overlaps with the second data line DLm such that a sum ofthe additional capacitance 202 and the third capacitance Cdp2 is atleast three times greater than the first capacitance Cdp1.

As described above, when the liquid crystal cell is driven by thehorizontal 2-dot inversion system, the LCD according to the thirdembodiment of the present invention allows the additional capacitance202 and the third parasitic capacitance Cdp2 at a right pixel 120, oftwo pixels having the same data polarity pattern, to be three timesgreater than the first parasitic capacitance Cdp1. Accordingly, at aleft pixel 110, an effect caused by a capacitance coupling of the firstparasitic capacitance Cdp1 is added to an effect caused by a capacitancecoupling of the second parasitic capacitance Cpd1. On the other hand, atthe right pixel 120, an effect caused by a capacitance coupling of thefourth parasitic capacitance Cpd2 is subtracted from an effect caused bya capacitance coupling of the third parasitic capacitance Cdp2 and aneffect caused by a capacitance coupling of the additional capacitance202, but an effect caused by the same capacitance coupling as the leftpixel 110 only is left because an effect caused by a capacitancecoupling of the third parasitic capacitance Cdp2 is relatively large.Thus, a deviation in the pixel voltage of the left pixel 110 and theright pixel 120 in the data polarity pattern is cancelled. Accordingly,the LCD according to the embodiment of the present invention does notgenerate a vertical dim phenomenon caused by the parasitic capacitancebetween the data line and the pixel electrode in the prior art.

Referring to FIG. 10, a liquid crystal cell of a liquid crystal display(LCD) according to a fourth embodiment of the present invention includesthin film transistors TFT provided at crossings of data lines DL andgate lines GL, and pixel electrodes PE connected to the thin filmtransistor TFT. The liquid crystal cell further includes a storagecapacitor Cst in order to make a stable maintenance of the charged pixelelectrode PE until the next pixel signal is charged.

The thin film transistor TFT has a gate electrode connected to the gateline GL, a source electrode connected to the data line DL and a drainelectrode connected to the pixel electrode PE. The thin film transistorTFT is turned on when a scanning signal, that is, a gate high voltageVgh from the gate line GL is applied, to thereby supply the liquidcrystal cell with a pixel signal from the data line DL. Further, thethin film transistor TFT is turned off when a gate low voltage Vgl fromthe gate line GL is applied, to thereby maintain a pixel signal chargedin the liquid crystal cell.

The pixel electrode PE is provided between the data lines DL andconnected to the thin film transistor TFT. Such an pixel electrode PE iscomprised of a first pixel electrode PE1 connected to the thin filmtransistor TFT provided at an intersection between the (m−1)th data lineDLm−1 and the gate line GL, and a second pixel electrode PE2 connectedto the thin film transistor TFT provided at an intersection between themth data line DLm and the gate line GL. In this case, the first pixelelectrode PE1 is arranged at the left side around the mth data line DLmwhile the second pixel electrode PE2 is arranged at the right sidearound the mth data line DLm.

The first pixel electrode PE1 is provided between the (m−1)th data lineDLm−1 and the mth data line DLm such that a distance between one sidethereof and the (m−1)th data line DLm−1 is equal to a distance betweenother opposite side thereof and the mth data line DLm. In this case, aparasitic capacitance is generated between the data line DL and thepixel electrode PE because they are adjacent to each other for astructure's sake. Such a parasitic capacitance causes a voltagevariation in the data line and a capacitance coupling after a pixelsignal was charged in the liquid crystal cell, thereby varying a pixelvoltage of the liquid crystal cell. The parasitic capacitance is dividedinto a first parasitic capacitance Cdp1 generated between the (m−1)thdata line and the first pixel electrode PE1 and a second parasiticcapacitance Cpd1 generated between the first pixel electrode PE1 and themth data line DLm.

The second pixel electrode PE2 is provided between the mth data line DLmand the (m+1)th data line DLm+1 such that a distance between one sidethereof and the mth data line DLm is equal to a distance between otheropposite side thereof and the (m+1)th data line DLm+1. In other words,one side of the second pixel electrode PE2 adjacent to the mth data lineDLm extends further into the mth data line DLm. In this case, a thirdparasitic capacitance Cdp2 is generated between the mth data line DLmand the second pixel electrode PE2 while a fourth parasitic capacitanceCpd2 is generated between the second pixel electrode PE2 and the (m+1)thdata line DLm+1. Thus, the third parasitic capacitance Cdp2 has at leastthree times larger value than the first parasitic capacitance Cdp1 ofthe first pixel electrode PE1. In other words, a distance W2 between oneside of the second pixel electrode PE2 and the mth data line DLm becomesnarrower than a width W1 between one side of the first pixel electrodePE1 and the (m−1)th data line DLm−1. Thus, the third parasiticcapacitance Cdp2 is at least three times greater than the firstparasitic capacitance Cdp1. On the other hand, the fourth parasiticcapacitance Cpd2 has the same value as the first parasitic capacitanceCdp1.

The liquid crystal cell provided with the first and second pixelelectrodes PE1 and PE2 is supplied with a data polarity pattern in thehorizontal 2-dot inversion driving system that is changed for each twoliquid crystal cells, that is, for each two dots in the horizontaldirection while being changed for each one dot in the verticaldirection. Accordingly, the first pixel electrode PE1 and the secondpixel electrode PE2 are supplied with the same data polarity pattern.

As described above, when the liquid crystal cell is driven by thehorizontal 2-dot inversion system, the LCD according to the fourthembodiment of the present invention allows the third parasiticcapacitance Cdp2 at a right pixel 120, of two pixels having the samedata polarity pattern, to be three times greater than the firstparasitic capacitance Cdp1. Accordingly, at a left pixel 110, an affectcaused by a capacitance coupling of the first parasitic capacitance Cdp1is added to an affect caused by a capacitance coupling of the secondparasitic capacitance Cpd1. On the other hand, at the right pixel 120,an effect caused by a capacitance coupling of the fourth parasiticcapacitance Cpd2 is subtracted from an effect caused by a capacitancecoupling of the third parasitic capacitance Cdp2, but an effect causedby the same capacitance coupling as the left pixel 110 only is leftbecause an effect caused by a capacitance coupling of the thirdparasitic capacitance Cdp2 is relatively large. Thus, a deviation in thepixel voltage of the left pixel 110 and the right pixel 120 in the datapolarity pattern is cancelled. Accordingly, the LCD according to theembodiment of the present invention does not generate a vertical dimmingphenomenon caused by the parasitic capacitance between the data line andthe pixel electrode in the prior art.

The second pixel electrode PE2 of the first and second pixel electrodesPE1 and PE2 includes a protrusion electrode 220 that extends toward themth data line DLm at the side surface thereof to overlap with a portionthereof.

At a left pixel 110 provided at the left side around the second dataline DLm in the liquid crystal cell, a first parasitic capacitance Cdp1is generated between the (m−1)th data line DLm−1 and the first pixelelectrode PE1 while a second parasitic capacitance Cpd1 is generatedbetween the first pixel electrode PE1 and the mth data line DLm. On theother hand, at a right pixel 120 provided at the right side around themth data line DLm in the liquid crystal cell, a third parasiticcapacitance Cdp2 is generated between the mth data line DLm and thesecond pixel electrode PE2 while a fourth parasitic capacitance Cpd2 isgenerated between the second pixel electrode PE2 and the (m+1)th dataline DLm+1. Further, at the right pixel 120, the second pixel electrodePE2 overlaps with the protrusion electrode 220 of the mth data line DLmto thereby generate an additional capacitance 222.

Thus, the third parasitic capacitance Cdp2 and the additionalcapacitance 222 generated between the mth data line DLm and the secondpixel electrode PE2 at the right pixel 120 is at least three timesgreater than the first parasitic capacitance Cdp1. To this end, theprotrusion electrode 220 overlaps with the mth data line DLm such that asum of the additional capacitance 222 and the third parasiticcapacitance Cdp2 is at least three times greater than the firstcapacitance Cdp1.

As described above, when the liquid crystal cell is driven by thehorizontal 2-dot inversion system, the LCD according to the fourthembodiment of the present invention allows third parasitic capacitanceCdp2 at a right pixel 120 of two pixels having the same data polaritypattern to be three times greater than the first parasitic capacitanceCdp1. Accordingly, at a left pixel 110, an effect caused by acapacitance coupling of the first parasitic capacitance Cdp1 is added toan effect caused by a capacitance coupling of the second parasiticcapacitance Cpd1. On the other hand, at the right pixel 120, an effectcaused by a capacitance coupling of the fourth parasitic capacitanceCpd2 is subtracted from an effect caused by a capacitance coupling ofthe third parasitic capacitance Cdp2 and an affect caused by acapacitance coupling of the additional capacitance 222, but an effectcaused by the same capacitance coupling as the left pixel 110 only isleft because an effect caused by a capacitance coupling of the thirdparasitic capacitance Cdp2 is relatively large. Thus, a deviation in thepixel voltage of the left pixel 110 and the right pixel 120 in the datapolarity pattern is cancelled. Accordingly, the LCD according to theembodiment of the present invention does not generate a vertical dimmingphenomenon caused by the parasitic capacitance between the data line andthe pixel electrode in the prior art.

As described above, the LCD according to the present invention includesthe pixel electrode set such that parasitic capacitance values betweenthe data lines are asymmetrical to each other. Further, the LCDaccording to the present invention includes the data lines having adifferent width from each other such that parasitic capacitance valuesbetween the data lines are asymmetrical to each other. Alternatively,the LCD according to the present invention includes the pixel electrodeprotruded toward the data line to overlap with a portion thereof suchthat parasitic capacitance values between the data lines areasymmetrical to each other. Otherwise, the LCD according to the presentinvention includes the data line protruded toward the pixel to overlapwith a portion thereof such that parasitic capacitance values betweenthe data lines are asymmetrical to each other.

Accordingly, the LCD according to the present invention does notgenerate a vertical dimming phenomenon caused by the parasiticcapacitance between the data line and the pixel in the horizontal 2-dotinversion system. As a result, the LCD according to the presentinvention can improve a picture quality of the liquid crystal displaypanel.

It will be apparent to those skilled in the art that variousmodifications and variation can be made in the present invention withoutdeparting from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A liquid crystal display device, comprising: a first data linesupplied with data; a second data line supplied with said data andhaving a different width from the first data line; a first pixelelectrode spaced at a desired distance from the first data line; and asecond pixel electrode spaced at a desired distance from the second dataline and spaced apart from the second data line by a distance differentfrom said distance between the first data line and the first pixelelectrode, wherein a parasitic capacitance between the second pixelelectrode and the second data line has at least three times larger valuethan a parasitic capacitance between the first pixel electrode and thefirst data line.
 2. The liquid crystal display device according to claim1, wherein the first pixel electrode and the second pixel electrode havea different size from each other.
 3. The liquid crystal display deviceaccording to claim 1, wherein the first and second pixel electrodes aresupplied with data having the same polarity.
 4. The liquid crystaldisplay device according to claim 1, wherein said data have datapolarity patterns inverted for each two pixel electrodes in thehorizontal direction while having data polarity patterns inverted foreach one pixel electrode in the vertical direction.
 5. A liquid crystaldisplay device, comprising: a first data line supplied with a signal; asecond data line supplied with said signal and parallel to the firstdata line; a protrusion electrode protruding from the second data line;a first pixel electrode spaced at a desired distance from the first dataline; and a second pixel electrode spaced at a desired distance from thesecond data line and overlapped with the protrusion electrode at aportion thereof so that parasitic capacitance between the second pixelelectrode and the second data line has at least three times larger valuethan a parasitic capacitance between the first pixel electrode and thefirst data line.
 6. The liquid crystal display device according to claim5, wherein the first pixel electrode has the same dimension as thesecond pixel electrode.
 7. The liquid crystal display device accordingto claim 5, wherein the first and second pixel electrodes are suppliedwith signals having the same polarity.
 8. The liquid crystal displaydevice according to claim 5, wherein said signals have polarity invertedfor each two pixel electrodes in the horizontal direction while havingpolarity inverted for each one pixel electrode in the verticaldirection.
 9. A liquid crystal display device, comprising: first andsecond data lines supplied with signals; a first pixel electrode spacedat a predetermined distance from the first data line; a second pixelelectrode spaced at a second predetermined distance from the second dataline; and a protrusion electrode protruded from the second pixelelectrode into the second data line and overlapped with the second dataline at a portion thereof so that parasitic capacitance between thesecond pixel electrode and the second data line has at least three timeslarger value than a parasitic capacitance between the first pixelelectrode and the first data line.
 10. The liquid crystal display deviceaccording to claim 9, wherein the first pixel electrode has the samedimension as the second pixel electrode.
 11. The liquid crystal displaydevice according to claim 9, wherein the first and second pixelelectrodes are supplied with signals having the same polarity.
 12. Theliquid crystal display device according to claim 9, wherein said signalshave polarity inverted for each two pixel electrodes in the horizontaldirection while having polarity inverted for each one pixel electrode inthe vertical direction.